In order to prepare solutions of lower concentrations for titration, and for qualitative analysis, a calculated volume of the concentrated solution is taken from the stock solution and then added to a specified volume of distilled water. However the volume of such a solution to be taken depends on the information provided by the manufacturer on the label pasted on the stock bottle. For instance; the label on the stock bottle of concentrated H2SO4.

Generally, the original molar concentration, Co of a chemical substance of molar mass, M grams per mole in a commercial product of P% by mass and of density (or specific gravity) d gram per cm3 is given as Co = (10 * P * d)/M or Co = 10Pd/M

Therefore, 2.78ml of concentrated H2SO4 will be required to prepare 0.1m of H2SO4 in 500ml.

CONCENTRATED LIQUID ANALYTICAL REAGENTS

REAGENT

% PURITY

R.M.M.

S.G. SPECIFIC GRAVITY

CH3COOH

99.5

60

1.05

NH3

35

17

0.88

HCl

36

36.5

1.18

HF

48

20

1.18

HNO3

70

63

1.42

HClO3

60

84.5

1.53

H3PO4

85

98

1.69

H2SO4

97 or 98

98

1.82

Side-Bench Reagents

The following is a list of reagents required to carry out chemical analysis, and which should be readily available in reagent bottles on the side-bench in the laboratory. The directions for preparing the solutions are given.

Note: When diluting any concentrated acid, always add Acid to Water – never add water to acid.

Calcium chloride, 0.5molar: Dissolve 55g of solid in water and make up to 1dm3.

2, 4-dinitrophenylhydrazine: Dissolve 2.0g of the solid in 10cm3 of concentrated H2SO4. Add this solution to 200cm3 of absolute ethanol, dilute to 500cm3 with water, thoroughly, allow to stand, then filter and use the filterate.

Fehling’s solution A: Dissolve 35g of hydrated CuSO4 in water, add few drops of concentrated H2SO4 and dilute to 500cm3 with water.

Starch solution: Make a paste with 1.0g of soluble starch in a small amount of water and add about 100cm3 of boiling water. Boil the mixture for a while to obtain a clear solution. Prepare when ready to use.

Lime water (Ca(OH)2(aq): Dissolve 25g of Ca(OH)2 in 1dm3 of distilled water, shake, stir and then keep with tight cover for a day, decant the clear and colourless solution later filter and later keep the filtrate in a corked reagent bottle.

Iodine solution: Dissolve 120g of solid iodine in 1000dm3 of distilled water to which 3.5g KI have been dissolved before.

Preparation of reagent in %w/w: It means a particular weight of a solute in 100g of solution. For example 98%w/w H2SO4 means: 98g of the acid (solute) is in 100g of solution, i.e. 100g of stock solution contains 98g of H2SO4.

Preparation of reagent in %w/v: It means a particular weight of a solute in 100cm3 of solution. For example, 20%w/vNa2CO3 means: 20g of Na2CO3 in 100cm3 of solution.

Preparation of reagent in %v/v: It means a particular volume of a solute in 100cm3 of solution. For example, 10%v/v acetone means: 10cm3 of acetone in 100cm3 of solution.

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Barium Chloride is used in the purification of water saturated solution in caustic chlorine plants and also in the Barium Chloride Exporters India manufacture of heat treatment salts, case hardening of steel